1. Technical Field
The technical field relates to an imaging apparatus including a camera body and an interchangeable lens, as well as a camera body and an interchangeable lens composing an imaging apparatus.
2. Related Art
There is an imaging apparatus including a camera body and an interchangeable lens mountable to the camera body (see, for example, JP-A-03-072308).
In the imaging apparatus described in JP-A-03-072308, the interchangeable lens is provided with a drive unit for driving a lens or a diaphragm according to an instruction from the camera body. In this configuration, the camera body can control the drive of a focus lens or the diaphragm by sending an instruction to the interchangeable lens.
Described below is the exchange of information between the camera body and the interchangeable lens in controlling by the camera body the drive of a member such as the focus lens in the interchangeable lens. In the following, the case where the camera body controls the drive of the focus lens and thereafter controls the drive of the diaphragm will be described as an example.
First, the camera body sends a control signal for driving the focus lens to the interchangeable lens. The interchangeable lens controls the drive unit to drive the focus lens based on the control signal. When the drive of the focus lens is completed, the interchangeable lens sends a signal indicating that the interchangeable lens is ready to accept next control to the camera body. When the camera body receives the signal indicating that the interchangeable lens is ready to accept next control, the camera body sends a control signal for driving the diaphragm to the interchangeable lens. Based on the control signal, the interchangeable lens controls the drive unit to drive the diaphragm. In this manner, the camera body can control the drive of the focus lens, and so on, in the interchangeable lens by sending control signals to the interchangeable lens.
When the focus lens and the diaphragm are separately driven, one of movable members (e.g., the focus lens) is driven and thereafter the other movable member (e.g., the diaphragm) is driven. Thus, there is a problem that it takes time to complete the drive of both the movable members. This problem will be specifically described with reference to FIG. 13.
First, when the camera body is instructed to start shooting by a user fully pressing a shutter switch, the camera body determines whether the focus lens and the diaphragm need to be driven. The case where the focus lens needs to be driven is, for example, a case where a focus position at exposure can be estimated based on the movement of a subject on a screen and the focus lens needs to be driven. The case where the diaphragm needs to be driven is, for example, a case where a diaphragm value at exposure (a diaphragm value different from that obtained upon full-press) has been set according to an operation by the user. When the camera body determines that both the focus lens and the diaphragm need to be driven, the camera body sends control signals to the interchangeable lens to drive the focus lens and the diaphragm.
When the camera body sends the interchangeable lens control signals to allow the interchangeable lens to perform operations one by one as described above, in the interchangeable lens, the focus lens is driven and thereafter the diaphragm is driven as shown in FIG. 13. It takes a long time to start exposure after the user fully presses the shutter switch, which is not desirable.
To avoid such inconvenience, it can be considered that the camera body may send two drive instructions (a focus lens drive instruction and a diaphragm drive instruction) in one piece of control information to the interchangeable lens. However, in data communication between the camera body and the interchangeable lens, the amount of data that can be communicated at one time is often limited. Hence, the camera body may not be able to send the interchangeable lens information for driving the diaphragm and information for driving the focus lens, as one instruction (control information). Accordingly, it is not effective to send two drive instructions to the interchangeable lens as one piece of control information.